This invention relates to a track jumping control apparatus for a disk drive system such as an optical disk drive system.
In optical disk drive systems, when the reproduction of information from an optical disk is required, an information reading laser light beam emitted from an optical pickup is moved so as to meet a track line part on which the information is recorded. This movement of the laser light beam is generally performed by a 2-stage drive mechanism including a coarse-motion motor and a fine-motion actuator. The coarse-motion motor executes a coarse seeking process. The fine-motion actuator executes a fine seeking process. During the coarse seeking process, a carriage including the optical pickup is moved to a target position by the coarse-motion motor. When the optical pickup moves to a position near a target track line part as a result of the coarse seeking process, the fine seeking process is started. During the fine seeking process, the laser light beam is repeatedly subjected to a step-jumping motion which corresponds to a radial displacement from a track line part to a neighboring track line part. Each step-jumping motion is realized by feeding a pair of a positive pulse current (a kick pulse current) and a negative pulse current (a brake pulse current) to the fine-motion actuator.
As will be explained later, a prior art apparatus for such track jumping control has some problem.